A working page isn't the same as a fast one — slow load times and janky interactions drive users away and hurt search rankings. This module covers Core Web Vitals as the metrics that matter, then the practical techniques for improving them: code splitting, image optimization, and caching.
Performance work pays off across every project you build. Work through these lessons in order, then move on to Deployment to ship what you've built.
The metrics Google and users actually care about — LCP, INP, and CLS — and what each one measures.
Profiling a real page with Lighthouse and browser DevTools to find out what's actually slow.
Shipping less JavaScript upfront by splitting bundles and loading code only when it's needed.
Choosing the right formats and sizes, and lazy-loading images that aren't on screen yet.
Using browser caching and CDNs so returning visitors don't re-download everything.
Finding and cutting dead code and heavy dependencies that are bloating your JavaScript bundle.
Avoiding layout thrashing and janky animations by understanding how the browser paints a frame.